CVE-2021-27290
HIGHCVE-2021-27290 is a high-severity (CVSS 7.5) vulnerability in ssri. 2 public exploit references exist, so weaponization risk is real. O3 Security confirms whether CVE-2021-27290 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regular Expression Denial of Service (ReDoS)
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
ssrinpmDescription
ssri 5.2.2-8.0.0, fixed in 8.0.1, processes SRIs using a regular expression which is vulnerable to a denial of service. Malicious SRIs could take an extremely long time to process, leading to denial of service. This issue only affects consumers using the strict option.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ssri | ≥ 5.2.2&&< 6.0.2 | 6.0.2 |
| 📦npm | ssri | ≥ 7.0.0&&< 7.1.1 | 7.1.1 |
| 📦npm | ssri | ≥ 8.0.0&&< 8.0.1 | 8.0.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ssri. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update ssri to 6.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-27290 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-27290 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-27290. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Whilst the OpenShift ServiceMesh (OSSM) servicemesh-grafana and servicemesh-prometheus include the vulnerable ssri library, the vulnerable "strict" option is not used. Similar to OSSM, OpenShift Container Platform (OCP), Red Hat Advance Cluster Management for Kubernetes (RHACM) and OpenShift distributed tracing…
Frequently Asked Questions
Is CVE-2021-27290 in your dependencies?
O3 detects CVE-2021-27290 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.